1. Field of the Invention
This invention relates to electronic systems for transferring data over a bus, and particularly to a system and method for burst broadcasting data from a single bus interface unit (BIU) to multiple other BIUs over a peripheral component interconnect (PCI) bus.
2. Description of Related Art
In current computer systems, it is necessary to transfer large amounts of data quickly between different peripheral devices, such as video graphics cards (30 Mbytes/sec), network interfaces (15 Mbytes/sec), and magnetic or optical disk drives (20 Mbytes/sec). The common high-speed electronic path that these peripheral devices share in exchanging data is called an input/output (I/O) bus, and the connections between the peripheral devices and the bus are called bus interface units (BIUs). When discussing data transfers, this specification refers to the peripheral devices and their associated BIUs interchangeably.
In many computer systems, the I/O bus often acts as a bottleneck, limiting the rate of data transfer. One relatively new I/O bus (released in 1992), designed with a high bandwidth (132 Mbytes/sec or more), is the peripheral component interconnect (PCI) bus. The PCI bus is described by PCI Local Bus Specification, revision 2.0, PCI Special Interest Group, Apr. 30, 1993, the entirety of which is incorporated herein by reference.
While it has significant advantages, one problem with the PCI bus is that it does not provide for burst-broadcasting data. "Broadcasting" means the simultaneous transfer of data from a single BIU to multiple other BIUs on the PCI bus. "Burst" means that the transfer can extend over multiple data phases, rather than being a single data phase. Although the PCI bus provides for a PCI Special Cycle in which a message can be broadcast to multiple devices, the PCI Special Cycle message can only be a single data phase. Consequently, it has not been possible to broadcast blocks of data to multiple devices concurrently. For example, if a network is to become unavailable for a period of time due to repairs, multiple messages must be sent to all other peer devices before the repair occurs. If the messages are lengthy, a significant amount of time may be required to sequentially access and communicate with each device.
In view of the foregoing, it is an object of the present invention to provide a data management system capable of burst-broadcasting data from a single peripheral device to multiple other peripheral devices.
It is another object of the invention to provide a data management system which can burst data both sequentially (one peripheral device at a time) and simultaneously (all peripherals devices at once).
It is another object of the invention to use the industry standard PCI bus protocol as a backbone for burst-broadcast data transfers.